Dr O'Sullivan's credentials are impressive. She is a Professor of International Affairs at Harvard and was an adviser to the Bush administration on Afghanistan and Iraq. Her time in Baghdad, which she left in 2007, is also remembered for risks she took to gauge opinion on the ground.

"While other Americans stayed in the fortified Green Zone, O'Sullivan donned conservative clothes, covered her bright-red hair with a scarf and ventured out with an Iraqi driver to see what was happening in the country," the Washington Post reported in a profile.

She is cool under pressure. When a rocket hit a room next to hers in the al-Rashid Hotel and debris blocked her door, she climbed out onto a ledge 10 storeys up and clambered to the safety of another window.

"This is Meghan O'Sullivan – just cool and collected and grace under pressure," said Robert Blackwill, her predecessor as George W Bush's chief Iraq adviser on the National Security Council (NSC). "She knows more about Iraq and its political personalities than anyone in the administration, which is probably saying anyone in the West," he added.

She will bring the same attention to detail and careful cultivation of local contacts to her work here. "I wouldn't be surprised if she turns up at clubs in Woodvale or Ardoyne," an OFMDFM source said.

The fly in the ointment is that Bush's Iraq policy is not considered a success. "The administration's policy has been a tragic failure, and she has been a central element of our policy-making," Larry Diamond, a Stanford University professor who became a critic of the President's handling of Iraq, told the Washington Post.

But he added that "the majority of the blame needs to rest at the foot of the higher officials".

Charles Landow, the other member of Dr Haass' team, has a background in the International Labour Organisation.

He is currently an associate director at the Council on Foreign Relations (CFR), the leading American think tank of which Dr Haass is President.